Lloyds Banking Group is transferring more than 4.6 million customers to the revived TSB - famous for its 1980s slogan "the bank that likes to say yes".
Its logo featuring white lettering on blue circles will replace the Lloyds black horse emblem as well as the Cheltenham and Gloucester brand at 631 branches.
The bank's mission statement harks back to the founding of the Trustee Savings Bank movement more than 200 years ago when the Reverend Henry Duncan created a "bank for hard-working local people".
Its focus on purely individual and small business customers seeks to align it firmly with the image of the dependable high street bank manager rather than the risk-taking "casino" traders of investment banking largely blamed for the financial crisis.
With 8,000 members of staff, TSB will have offices in Birmingham, Gloucester, Edinburgh, London and Bristol, with call centres in Swansea, Sunderland, Edinburgh and Gloucester.
He has described it as a "completely clean bank" untainted by the turbulence that has threatened to overwhelm the financial sector in recent years.
Unlike its parent, TSB will not be encumbered by claims over mis-selling of payment protection insurance or complex interest rate swap products.
It will also be free of the toxic assets acquired by Lloyds' acquisition of HBOS at the height of the financial crisis and ultimately saw it being bailed out by the taxpayer.
Lloyds Banking Group remains 39% state-owned and its disposal of TSB is a legacy of its troubled recent past when it was compelled to spin off the branches as part of EU rules on state aid.
Executives managing the disposal of the network - dubbed Project Verde - will be hoping for a headache-free transition after plans to sell it to the Co-op collapsed earlier this year.
It should mark the latest step on the road to recovery for Lloyds, which said last month that it was ready for the Government to fire the starting gun on the sale of its stake after swinging out of the red with half-year profits of more than £2 billion.
TSB's website went live last month but customers holding one of its eight million accounts will not be able to log in until Sunday, a day before the launch. Their passwords will remain the same.
Lloyds plans to float the business in the middle of next year. For the time being it will offer the same products as its parent, with new deals expected later.
Any customers unhappy about moving to TSB have been told they can choose to stay with Lloyds - and 4,000 have already done so. However, 600 have made an unprompted decision to switch to the new bank.
TSB says it can trace its heritage back to the foundation of a self-supporting savings bank in 1810 by the Reverend Henry Duncan in Ruthwell, Dumfriesshire.
Savings banks operated independently until they were brought together in the 1970s, followed by a stock exchange flotation in 1986 and the creation of TSB Group. The group merged with Lloyds Bank in 1995 to form Lloyds TSB.
The new bank's mission statement says: "TSB will be different from other banks in that it is purely focused on individuals, families and local businesses in the communities we serve across Britain."
Its chief executive, Paul Pester, previously led the team that created Virgin Money banking brand in the UK.